greybus: make: check kernel configuration options

Add checks for options that shall be enabled in the kernel config
and for options that shall be disable.

To add options to list append them to CONFIG_OPTIONS_ENABLE or
CONFIG_OPTIONS_DISABLE respectively.
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/Makefile

@@ -44,6 +44,22 @@ KERNELDIR 		?= /lib/modules/$(KERNELVER)/build
 INSTALL_MOD_PATH	?= /..
 PWD			:= $(shell pwd)
 
+# kernel config option that shall be enable
+CONFIG_OPTIONS_ENABLE := SYSFS SPI USB SND_SOC
+
+# kernel config option that shall be disable
+CONFIG_OPTIONS_DISABLE :=
+
+# this only run in kbuild part of the makefile
+ifneq ($(KERNELRELEASE),)
+$(foreach opt,$(CONFIG_OPTIONS_ENABLE),$(if $(CONFIG_$(opt)),, \
+     $(error CONFIG_$(opt) is disabled in the kernel configuration and must be enable \
+     to continue compilation)))
+$(foreach opt,$(CONFIG_OPTIONS_DISABLE),$(if $(filter m y, $(CONFIG_$(opt))), \
+     $(error CONFIG_$(opt) is enabled in the kernel configuration and must be disable \
+     to continue compilation),))
+endif
+
 # add -Wall to try to catch everything we can.
 ccFlags-y := -Wall